Black Widow

In the United States, we have two spiders that could pose a threat to a human, if bitten. One of those is the Black Widow spider, so called because they are usually black in color and because the female sometimes eats the male after mating (especially if she has not eaten recently). The other problematic species here is the Brown Recluse (Loxosceles spp.). I've seen Black Widows several times in my life, but this one posed nicely on our back door frame so I could get a good shot of her.

I was thrilled to have caught the reflection of the spider in the glass! Not only does that help make the shot artistic in appearance, but also allows the profile of the spider to be seen as well as a dorsal view. This is definitely a female, as the males are smaller, are often more brownish in color, and do not have the distinctive red markings of the females. Those red markings of the females are often in the shape of an hourglass (see photo at right), almost like two triangles with points touching, but some have red spots, instead, like the one I photographed, above.

Black Widow spiders can cause sickness in some humans, but the bite is not often fatal in healthy people. Sometimes, a spider will bite without injecting any venom, which is known as a "dry bite." Sickness will occur only if venom is present in the bite. Symptoms of a bite can include generalized pain at the site of the bite, nausea/vomiting, muscle pain or stiffness, and stomach cramps. Symptoms will usually subside after three-to-six days, on their own, and anti-venom is typically administered only if the pain is severe.

The manufacture of the anti-venom is a curious process:

Antivenom is made by injecting horses with latrodectus venom over a period of time. The horse develops antibodies against the venom. The horse is bled and the antibodies purified for later use. Doctors recommend the use of anti-inflammatory medications before antivenom administration, because antivenom can induce allergic reactions to the horse proteins.^[1]

It amazes me how humans can think of such things. The methodology stymies me sometimes, too — e.g., why a horse? Did someone try it with a cow or a goat and it didn't work? Or is there something specific about the immune system of a horse that makes it ideal? There are always so many questions and so few answers for a curious kitty to obtain! 😜

I was also surprised when I read of the distribution of the Widow spiders:

Widow spiders can be found on every continent of the world except Antarctica. In North America, the black widows commonly known as southern (Latrodectus mactans), western (Latrodectus hesperus), and northern (Latrodectus variolus) can be found in the United States, as well as parts of southern Canada – particularly in the Okanagan Valley of British Columbia, as can the "gray" or "brown widow spiders" (Latrodectus geometricus) and the "red widow spiders" (Latrodectus bishopi).

The species that we have in the southeastern US is (Latrodectus mactans), or the Southern Black Widow (although we just say "Black Widow"). They live fairly close to the ground and are frequently found around wood piles, so gloves are advised when bringing firewood indoors for the winter — and check the logs before bringing them indoors, too!